POPE Francis, celebrating his first Christmas as Roman Catholic leader, has called on atheists to unite with believers of all religions and work for "a home-made peace" that can spread across the world.
Speaking to about 70,000 people from the central balcony of St Peter's Basilica -- the same spot where he emerged to the world as pontiff when he was elected on March 13 -- Francis also made another appeal for the environment to be saved from "human greed and rapacity".
The leader of the 1.2 billion-member church wove his first 'Urbi et Orbi' (to the city and world) message around the theme of peace.
"Peace is a daily commitment. It is a home-made peace," he said.
He said people of other religions were also praying for peace, and -- departing from his prepared text -- he urged atheists to join forces with believers.
"I invite even non-believers to desire peace. Join us with your desire, a desire that widens the heart," he said, drawing sustained applause from the crowd.
"Let us all unite, either with prayer or with desire, but everyone, for peace."
Francis's reaching out to atheists and people of other religions is in marked contrast to the attitude of former Pope Benedict, who sometimes left non-Catholics feeling he saw them as second-class believers.
Francis called for "social harmony in South Sudan, where current tensions have already caused numerous victims and are threatening peaceful coexistence in that young state".
Thousands are believed to have died in violence divided along ethnic lines between the Nuer and Dinka tribes in the country, which seceded from Sudan in 2011 after decades of war.
The Pope also called for dialogue to end the conflicts in Syria, Nigeria, the Democratic Republic of Congo and Iraq, and prayed for a "favourable outcome" to the peace process between Israelis and Palestinians.
"Wars shatter and hurt so many lives," he said, saying their most vulnerable victims were children, the elderly, and the sick.